<svg x="0" y="0" viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
  <symbol id="moon">
    <path d="M28.43,0A28.44,28.44,0,0,1,32.3,14.32,28.61,28.61,0,0,1,3.69,42.93,28.71,28.71,0,0,1,0,42.66,28.59,28.59,0,1,0,28.43,0Z" fill="url(#moon-grad)"></path>
  </symbol>

  <defs>
    <linearGradient id="moon-grad" x1="0%" y1="50%" x2="100%" y2="0%">
      <stop offset="0%" stop-color="#686e73" />
      <stop offset="100%" stop-color="#6a7075" />
    </linearGradient>
  </defs>
  <symbol id="s01n">
    <use xlink:href="#moon"  x="0" y="0" width="100" height="100" transform="translate(20,20) scale(1,1)"></use>
  </symbol>
  <use xlink:href="#s01n" x="0" y="0" width="100" height="100"></use>
</svg>